ISS refers to the Interchangeable Stringer System. ISS allows the rider of an ISS bodyboard to change their stringer and therefore their flex dependant on circumstance. For example, in colder water one might prefer a softer stringer, whereas in warmer conditions one might prefer something quite the opposite. You might like to optimise your control when facing bigger and heavier waves. It doesn’t matter. What matters is that ISS gives you the capability to change how much your board flexes depending on your own personal preference. All ISS---- boards incorporate a lightweight, high strength polymer tube which forms a flexible sleeve insulating the stringer cavity from the core of the board. In simpler terms, your board has a hole lined with plastic through the centre, it won’t affect performance of the board in any way shape or form unless you of course change your flex. Stringers load in to an empty ISS chamber and simply screw in clockwise. The rest is history. Travel the world and surf different waves, temperatures and conditions with one board and three stringers.
Note that all stringers are sold separately. All ISS bodyboards come with a standard issue stringer. To begin with these boards are the exact same as any other non-ISS bodyboard you might have purchased. It’s up to you to change the flex of the bodyboard as you see fit.